-
Fabio Benfenati, MD
Professor of Neurophysiology, University of Genova
Research Director, Department of Neuroscience and Neurotechnologies
Department of Neuroscience and Brain Technologies, The Italian Institute of
Technology, Genova, Via Morego 30
16163 Genova – Italy
Contact information: phone +39-01071781434 fax +39-01071781230 email fabio.benfenati@iit.it
Short biography
Fabio Benfenati received the MD in 1979 and PhD in Neurology in 1983. His training was as post-doc at the Karolinska Institutet (Stockholm, Sweden) and as research associate and faculty member at the Laboratory of Molecular and
Cellular Neuroscience of The Rockefeller University (New York). He is currently full professor of Neurophysiology, University of Genova, School of
Medicine (Italy) and head of the Department of Neuroscience and Brain
Technologies, at the Italian Institute of Technology (Genova, Italy). He has been President of the Italian Society of Neuroscience (2003-2005) and of the
Italian Physiological Society (2009-2011) and is associate editor of Frontiers in Neuroengineering. Fabio Benfenati has a long-standing experience in cellular neurophysiology. He has recently used the most advanced electrophysiological and optical techniques to study the cellular mechanisms of neural plasticity and create neuro-hybrid interfaces with inorganic and organic substrates that stimulate and/or compute neuronal activity. An important part of the research had recently been devoted to exploit optogenetic and opto-stimulation techniques.
Title of the talk
Polymeric neurointerfaces for modulation of neural activity: Toward a Bio-
Organic artificial retina
Abstract of the talk

Sight restoration is one of the new frontiers for prosthetic devices that enable the electrical stimulation of neurons. In particular, diseases that affect the retinal pigment epithelium and photoreceptors but preserve the inner retinal layers are preferential targets for implantation of visual prostheses. We recently discovered that primary neurons can be successfully grown onto a transparent photovoltaic organic polymer and electrically stimulated by light.
This result encouraged us to test the efficacy of this method in retinas explanted from albino rats with reproducibly induced photoreceptor degeneration due to light damage. We investigated the ability of the polymer layer to restore light sensitivity in retinas explanted from albino rats with a light-induced degeneration of the photoreceptor layer. Acutely dissected retinas were placed on the organic polymer in a sub-retinal configuration (i.e., external layers in contact with the polymer). Light stimulation of the degenerate retina was observed by monitoring multi-unit activity and filed potentials with an extracellular electrode positioned in the retinal ganglion cell layer. Multi-unit activity recordings showed that a light stimulus 16-fold lower than the safe limit for pulsed illumination elicited intense spiking activity in degenerate retinas placed on polymer-coated substrates to levels indistinguishable from those recorded in control retinas. Moreover, to evaluate the efficiency of the interface, a dose-response analysis of spiking activity versus light intensity was performed in degenerate retinas. Spiking activity was observed in degenerate retinas over the polymer with a response threshold below 0.3 μW/mm2, a linear increase in a range corresponding to daylight irradiance, and a response saturati on above 100 μW/mm2
(considered the safe limit for chronic illumination). A 4-fold increase in the amplitude of the light response at saturation and a significant left shift of the dose-response curves were obtained in retinas placed over the polymercoated interface respect to degenerate retinas on glass substrates.
Our finding indicated that the interface fully mimicked functional photoreceptors in activating the processing of the inner retina and was able to rescue normal light sensitivity. These results broaden the possibility of developing a new generation of fully organic prosthetic devices for sub-retinal implants.